ext4: handle ext4_mark_inode_dirty errors

ext4_mark_inode_dirty() can fail for real reasons. Ignoring its return
value may lead ext4 to ignore real failures that would result in
corruption / crashes. Harden ext4_mark_inode_dirty error paths to fail
as soon as possible and return errors to the caller whenever
appropriate.

One of the possible scnearios when this bug could affected is that
while creating a new inode, its directory entry gets added
successfully but while writing the inode itself mark_inode_dirty
returns error which is ignored. This would result in inconsistency
that the directory entry points to a non-existent inode.

Ran gce-xfstests smoke tests and verified that there were no
regressions.

Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20200427013438.219117-1-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 20 insertions, 14 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 5809891eadabb5..49ea6973d65fad 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -816,7 +816,7 @@ ext4_ext_binsearch(struct inode *inode,
 
 }
 
-int ext4_ext_tree_init(handle_t *handle, struct inode *inode)
+void ext4_ext_tree_init(handle_t *handle, struct inode *inode)
 {
 	struct ext4_extent_header *eh;
 
@@ -826,7 +826,6 @@ int ext4_ext_tree_init(handle_t *handle, struct inode *inode)
 	eh->eh_magic = EXT4_EXT_MAGIC;
 	eh->eh_max = cpu_to_le16(ext4_ext_space_root(inode, 0));
 	ext4_mark_inode_dirty(handle, inode);
-	return 0;
 }
 
 struct ext4_ext_path *
@@ -1319,7 +1318,7 @@ static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
 		  ext4_idx_pblock(EXT_FIRST_INDEX(neh)));
 
 	le16_add_cpu(&neh->eh_depth, 1);
-	ext4_mark_inode_dirty(handle, inode);
+	err = ext4_mark_inode_dirty(handle, inode);
 out:
 	brelse(bh);
 
@@ -4363,7 +4362,7 @@ static int ext4_alloc_file_blocks(struct file *file, ext4_lblk_t offset,
 	struct inode *inode = file_inode(file);
 	handle_t *handle;
 	int ret = 0;
-	int ret2 = 0;
+	int ret2 = 0, ret3 = 0;
 	int retries = 0;
 	int depth = 0;
 	struct ext4_map_blocks map;
@@ -4423,10 +4422,11 @@ retry:
 			if (ext4_update_inode_size(inode, epos) & 0x1)
 				inode->i_mtime = inode->i_ctime;
 		}
-		ext4_mark_inode_dirty(handle, inode);
+		ret2 = ext4_mark_inode_dirty(handle, inode);
 		ext4_update_inode_fsync_trans(handle, inode, 1);
-		ret2 = ext4_journal_stop(handle);
-		if (ret2)
+		ret3 = ext4_journal_stop(handle);
+		ret2 = ret3 ? ret3 : ret2;
+		if (unlikely(ret2))
 			break;
 	}
 	if (ret == -ENOSPC &&
@@ -4575,7 +4575,9 @@ static long ext4_zero_range(struct file *file, loff_t offset,
 	inode->i_mtime = inode->i_ctime = current_time(inode);
 	if (new_size)
 		ext4_update_inode_size(inode, new_size);
-	ext4_mark_inode_dirty(handle, inode);
+	ret = ext4_mark_inode_dirty(handle, inode);
+	if (unlikely(ret))
+		goto out_handle;
 
 	/* Zero out partial block at the edges of the range */
 	ret = ext4_zero_partial_blocks(handle, inode, offset, len);
@@ -4585,6 +4587,7 @@ static long ext4_zero_range(struct file *file, loff_t offset,
 	if (file->f_flags & O_SYNC)
 		ext4_handle_sync(handle);
 
+out_handle:
 	ext4_journal_stop(handle);
 out_mutex:
 	inode_unlock(inode);
@@ -4696,8 +4699,7 @@ int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
 				   loff_t offset, ssize_t len)
 {
 	unsigned int max_blocks;
-	int ret = 0;
-	int ret2 = 0;
+	int ret = 0, ret2 = 0, ret3 = 0;
 	struct ext4_map_blocks map;
 	unsigned int blkbits = inode->i_blkbits;
 	unsigned int credits = 0;
@@ -4730,9 +4732,13 @@ int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
 				     "ext4_ext_map_blocks returned %d",
 				     inode->i_ino, map.m_lblk,
 				     map.m_len, ret);
-		ext4_mark_inode_dirty(handle, inode);
-		if (credits)
-			ret2 = ext4_journal_stop(handle);
+		ret2 = ext4_mark_inode_dirty(handle, inode);
+		if (credits) {
+			ret3 = ext4_journal_stop(handle);
+			if (unlikely(ret3))
+				ret2 = ret3;
+		}
+
 		if (ret <= 0 || ret2)
 			break;
 	}
@@ -5269,7 +5275,7 @@ static int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
 	if (IS_SYNC(inode))
 		ext4_handle_sync(handle);
 	inode->i_mtime = inode->i_ctime = current_time(inode);
-	ext4_mark_inode_dirty(handle, inode);
+	ret = ext4_mark_inode_dirty(handle, inode);
 	ext4_update_inode_fsync_trans(handle, inode, 1);
 
 out_stop: